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344 results on '"Iwase, Hiroki"'

4. Polyelectrolyte-protein synergism: pH-responsive polyelectrolyte/insulin complexes as versatile carriers for targeted protein and drug delivery

Author

Murmiliuk, Anastasiia, Iwase, Hiroki, Kang, Jia-Jhen, Mohanakumar, Shilpa, Appavou, Marie-Sousai, Wood, Kathleen, Almásy, László, Len, Adél, Schwärzer, Kuno, Allgaier, Jürgen, Dulle, Martin, Gensch, Thomas, Förster, Beate, Ito, Kanae, Nakagawa, Hiroshi, Wiegand, Simone, Förster, Stephan, and Radulescu, Aurel

Published
2024
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9. Effects of Heterogeneous Mixing of Imidazolium-Based Ionic Liquids with Alcohols on Complex Formation of Ni(II) Ion

Author

Takamuku, Toshiyuki, Ogawa, Akira, Tsutsui, Sou, Sadakane, Koichiro, Iwase, Hiroki, Mayumi, Koichi, and Ozutsumi, Kazuhiko

Abstract

Understanding the complex formation of metal ions in room-temperature ionic liquids (ILs) is essential for the application of ILs in solvent extraction. Nevertheless, the research on metal complex formation in ILs lags behind other applications. The complex formation equilibria may be influenced by specific interactions among the metal ion, ligand molecule, and IL cation and anion. In the present investigation, the complex formation of Ni2+with ethanol (EtOH) and methanol (MeOH) molecules in ILs, 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([CNmim][TFSA], where Nrepresents the alkyl chain lengths of 2 and 8) was discussed in terms of the microscopic interactions among alcohol molecules, [CNmim]+and [TFSA]−, and the mesoscopic mixing states of alcohols in [CNmim][TFSA], with N= 2–12. The microscopic interaction of alcohol molecules with the imidazolium ring H atoms in the ILs was evaluated by using ATR–IR and 1H and 13C NMR spectroscopies. The self-hydrogen bonding of alcohol molecules was clarified from the O–H stretching vibration of alcohol molecules. MeOH molecules can be more strongly hydrogen-bonded with themselves than EtOH molecules due to the less steric hindrance and the weaker dispersion force of MeOH with the IL cation’s alkyl chain. In fact, small-angle neutron scattering (SANS) experiments revealed the more heterogeneous mixing of MeOH with the ILs by the self-hydrogen bonding among MeOH molecules than EtOH. The longer the IL cation’s alkyl chain, the more the MeOH clusters significantly form. In contrast, the formation of EtOH clusters becomes weaker with elongating the alkyl chain. Ultraviolet (UV)–visible spectroscopic measurements on Ni2+–[CNmim][TFSA]–alcohol solutions with N= 2 and 8 revealed that di-, tetra-, and hexa-alcohol–Ni2+complexes are formed in both the ILs. With N= 2, the stabilities of Ni2+–EtOH and Ni2+–MeOH complexes are comparable in the IL. However, with N= 8, the complexes are more stable in the EtOH solutions than in the MeOH solutions. This is because the less heterogeneous mixing of EtOH molecules with the IL results in the larger enthalpic contribution in the complex formation, as shown by the thermodynamic parameters estimated by the van’t Hoff plots on the stability constants at several temperatures.

Published
2024
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10. Low‐background ultrahigh‐purity aluminium window for small‐angle neutron scattering using monochromatic cold neutrons.

Author

Kumada, Takayuki, Motokawa, Ryuhei, and Iwase, Hiroki

Subjects
SMALL-angle neutron scattering, NEUTRONS, ALUMINUM, FRACTURE strength, TENSILE strength
Abstract

The 500 mm‐diameter aluminium alloy neutron window in the SANS diffractometer SANS‐J at JRR‐3, Tokai, Japan, has been replaced by an ultrahigh‐purity aluminium (5N‐Al, >99.999%) window. Although the 5N‐Al window is three times thicker than the alloy window to compensate for the lower tensile strength, the background intensity in the small‐angle neutron scattering (SANS) curve was successfully decreased by a factor of 10 at the maximum. The 5N‐Al window is suitable not only for large‐diameter neutron windows in SANS diffractometers but also for windows in their environmental apparatus which cannot be made of single‐crystal silicon or other ceramics due to their poor availability, fracture strength, processability or affinity with metallic materials. [ABSTRACT FROM AUTHOR]

Published
2024
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12. Evidence of a Rod-like Structure for Hydroxypropyl Cellulose Samples in Aqueous Solution

Author

Yoshida, Misato, Iwase, Hiroki, Horikawa, Yoshiki, and Shikata, Toshiyuki

Abstract

Because hydroxypropyl cellulose (HpC) is a popular polymeric material that forms a liquid crystalline phase in solutions with various kinds of solvents, including water, it is commonly thought that HpC has a typical rod-like structure in solution. In this study, the structures of commercial HpC samples in aqueous solution with average molar substitution numbers (MS) ranging from 3.6 to 3.9 and weight-average molar masses (Mw) ranging from 36 to 740 kg mol–1were investigated in detail. We first used multiple techniques, including standard static and dynamic light scattering (SLS and DLS), neutron and X-ray scattering experiments, and viscometric measurements, to obtain clear evidence of rod-like structures quantitatively. The dependence of excess scattering intensities for HpC samples under dilute conditions on the magnitude of the scattering vector over a wide range from 8.9 × 10–3to 3.0 × 10 nm–1was reasonably described by the form factor of rod particles with length (L) and diameter (d). Although the determined Lvalue was close to the contour length (lc) calculated from the Mwvalues in the lower Mwrange, Lbecame obviously less than lcwith increasing Mw. The radius of gyration (Rg) determined via SLS measurements was proportional to Lby a factor of approximately 3.5 ∼ √12 over the Mwrange examined. These observations revealed that the conformation of HpC molecules changes from an elongated single chain to a certain folded structure, maintaining the shape of the rod-shaped particles. Moreover, the Mwdependencies of the intrinsic viscosities and translational diffusion coefficients of the HpC samples resulting from DLS measurements were reasonably described with a theoretical rod-like particle model, assuming that Land dare identical to those resulting from the scattering behaviors.

Published
2024
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17. A high‐temperature high‐pressure small‐angle neutron scattering cell for studying hydrothermal reactions in supercritical water.

Author

Abe, Jun, Arima-Osonoi, Hiroshi, Iwase, Hiroki, Takata, Shin-ichi, Ohuchi, Kei-ichi, Kasai, Satoshi, Miyazaki, Tsukasa, Morita, Takeshi, and Shibayama, Mitsuhiro

Subjects
SMALL-angle neutron scattering, SUPERCRITICAL water, DEUTERIUM oxide, CELL analysis, COORDINATION polymers
Abstract

A high‐temperature high‐pressure cell equipped with a metallic window was developed for small‐angle neutron scattering (SANS). The feasibility of a Ti alloy (Ti–6Al–4V) as a candidate window material was assessed, considering its mechanical strength and neutron characteristics. SANS experiments should be conducted using safe and reliable materials without risk of window damage or leakage of the activated samples due to window breakage. SANS profiles measured for supercritical heavy water showed maximum scattering intensity at temperatures and pressures near the critical density. Additionally, the utility of the cell for observations of the decomposition of plastic in supercritical water is presented. The cell facilitates analysis of reaction mechanisms under sub‐ and supercritical conditions, which could provide detailed information to aid efficient decomposition and recycling, contributing to a sustainable society. [ABSTRACT FROM AUTHOR]

Published
2024
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18. Development of a D2O/H2O vapor generator for contrast-variation neutron scattering

Author

Arima-Osonoi, Hiroshi, primary, Takata, Shin-ichi, additional, Kasai, Satoshi, additional, Ohuchi, Keiichi, additional, Morikawa, Toshiaki, additional, Miyata, Noboru, additional, Miyazaki, Tsukasa, additional, Aoki, Hiroyuki, additional, Iwase, Hiroki, additional, Hiroi, Kosuke, additional, Ogura, Masao, additional, Kikuchi, Takashi, additional, Takashina, Hideo, additional, and Sakayori, Takahiro, additional

Published
2023
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19. Upgrade of the small-angle neutron scattering diffractometer SANS-J at JRR-3

Author

Kumada, Takayuki, primary, Motokawa, Ryuhei, additional, Oba, Yojiro, additional, Nakagawa, Hiroshi, additional, Sekine, Yurina, additional, Micheau, Cyril, additional, Ueda, Yuki, additional, Sugita, Tsuyoshi, additional, Birumachi, Atsushi, additional, Sasaki, Miki, additional, Hiroi, Kosuke, additional, and Iwase, Hiroki, additional

Published
2023
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26. Extended Q-range small-angle neutron scattering to understand the morphology of proton-exchange membranes: the case of the functionalized syndiotactic-polystyrene model system

Author

Schiavone, Maria-Maddalena, primary, Lamparelli, David Hermann, additional, Daniel, Christophe, additional, Golla, Manuchar, additional, Zhao, Yue, additional, Iwase, Hiroki, additional, Arima-Osonoi, Hiroshi, additional, Takata, Shin-ichi, additional, Szentmiklosi, Laszlo, additional, Maroti, Boglarka, additional, Allgaier, Jürgen, additional, and Radulescu, Aurel, additional

Published
2023
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28. Development of a D2O/H2O vapor generator for contrast‐variation neutron scattering.

Author

Arima-Osonoi, Hiroshi, Takata, Shin-ichi, Kasai, Satoshi, Ohuchi, Keiichi, Morikawa, Toshiaki, Miyata, Noboru, Miyazaki, Tsukasa, Aoki, Hiroyuki, Iwase, Hiroki, Hiroi, Kosuke, Ogura, Masao, Kikuchi, Takashi, Takashina, Hideo, and Sakayori, Takahiro

Subjects
NEUTRON generators, NEUTRON scattering, PROTON exchange membrane fuel cells, DEUTERIUM, SMALL-angle neutron scattering, VAPORS, INELASTIC neutron scattering, NEUTRON reflectivity
Abstract

The contrast‐variation technique in neutron scattering experiments plays a pivotal role in distinguishing partial structures within multi‐component complexes, facilitating the elucidation of distinct sample constituents. This differentiation is achieved using different isotopes, namely hydrogen and deuterium, which possess varying neutron scattering characteristics. This study presents a novel vapor generator designed for neutron scattering experiments, enabling continuous control of the D2O/H2O ratio of the vapor. This feature is especially useful for contrast‐variation studies. The generator features two saturators and four mass flow controllers, allowing for the rapid and independent generation of D2O/H2O vapors. Additionally, the incorporation of the two‐temperature method ensures accurate dew point control within a margin of ±0.2°Cdp. This setup proves useful for conducting time‐resolved experiments and can accelerate research on functional polymers, such as polymer electrolyte membranes for fuel cells, where water potential assumes critical importance. [ABSTRACT FROM AUTHOR]

Published
2023
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38. Star-Polymer-DNA Gels Showing Highly Predictable and Tunable Mechanical Responses

Author

Ohira, Masashi, Katashima, Takuya, Naito, Mitsuru, Aoki, Daisuke, Yoshikawa, Yusuke, Iwase, Hiroki, Takata, Shin-Ichi, Miyata, Kanjiro, Chung, Ung-Il, Sakai, Takamasa, Shibayama, Mitsuhiro, 1000030759840, Li, Xiang, Ohira, Masashi, Katashima, Takuya, Naito, Mitsuru, Aoki, Daisuke, Yoshikawa, Yusuke, Iwase, Hiroki, Takata, Shin-Ichi, Miyata, Kanjiro, Chung, Ung-Il, Sakai, Takamasa, Shibayama, Mitsuhiro, 1000030759840, and Li, Xiang

Abstract

Dynamically crosslinked gels are appealing materials for applications that require time-dependent mechanical responses. DNA duplexes are ideal crosslinkers for building such gels because of their excellent sequence addressability and flexible tunability in bond energy. However, the mechanical responses of most DNA gels are complicated and unpredictable. Here, a DNA gel with a highly homogeneous gel network and well predictable mechanical behaviors is demonstrated by using a pair of star-polymer-DNA precursors with presimulated DNA sequences showing the two-state transition. The melting curve analysis of the DNA gels reveals the good correspondence between the thermodynamic potentials of the DNA crosslinkers and the presimulated values by DNA calculators. Stress-relaxation tests and dissociation kinetics measurements show that the macroscopic relaxation time of the DNA gels is approximately equal to the lifetime of the DNA crosslinkers over 4 orders of magnitude from 0.1-2000 s. Furthermore, a series of durability tests find the DNA gels are hysteresis-less and self-healable after the applications of repeated temperature and mechanical stimuli. These results demonstrate the great potential of star-polymer-DNA precursors for building gels with predictable and tunable viscoelastic properties, suitable for applications such as stress-response extracellular matrices, injectable solids, and soft robotics.

Published
2022

39. On the proton conduction pathways in polyelectrolyte mem-branes based on syndiotactic-polystyrene

Author

Maria-Maddalena, Schiavone, Zhao, Yue, Iwase, Hiroki, Hiroshi, Arima-Osonoi, Shin-ichi, Takata, Radulescu, Aurel, Maria-Maddalena, Schiavone, Zhao, Yue, Iwase, Hiroki, Hiroshi, Arima-Osonoi, Shin-ichi, Takata, and Radulescu, Aurel

Abstract

When functionalized by solid-state sulfonation process, the amorphous regions of the semi-crystalline syndiotactic-polystyrene (sPS) become hydrophilic, thus can conduct protons upon membrane hydration, which increases the interest in this material as a potential candidate for applications with proton exchange membranes. The resistance of sulfonated sPS to oxidative decomposition can be improved by doping the membrane with fullerenes. In previous work we have described the morphology in hydrated sulfonated sPS films doped with fullerenes on dif-ferent length scales as determined by small angle neutron scattering (SANS) and the structural changes in such membranes as a function of the degree of hydration and temperature. In the current work we report on the relationship between the morphology of hydrated domains as obtained by SANS and the proton conductivity in sulfonated sPS-fullerene composite mem-branes at different temperature and RH conditions. Based on this combined experimental ap-proach, clear evidence for the formation and evolution of the hydrated domains in functional-ized sPS membranes has been provided and a better understanding of the hydration and conduc-tivity pathways in this material has been obtained.

Published
2022

42. Giant Carbon Nano-Test Tubes as Versatile Imaging Vessels for High-Resolution and In Situ Observation of Proteins

Author

Chuong, Tracy T., primary, Ogura, Toshihiko, additional, Hiyoshi, Norihito, additional, Takahashi, Kazuma, additional, Lee, Sangho, additional, Hiraga, Keita, additional, Iwase, Hiroki, additional, Yamaguchi, Akira, additional, Kamagata, Kiyoto, additional, Mano, Eriko, additional, Hamakawa, Satoshi, additional, Nishihara, Hirotomo, additional, Kyotani, Takashi, additional, Stucky, Galen D., additional, and Itoh, Tetsuji, additional

Published
2022
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47. Effects of self-hydrogen bonding among formamide molecules on the UCST-type liquid–liquid phase separation of binary solutions with imidazolium-based ionic liquid, [Cnmim][TFSI], studied by NMR, IR, MD simulations, and SANS

Author

Kawano, Masahiro, primary, Tashiro, Atsuya, additional, Imamura, Yuki, additional, Yamada, Moeno, additional, Sadakane, Koichiro, additional, Iwase, Hiroki, additional, Matsugami, Masaru, additional, Marekha, Bogdan A., additional, Idrissi, Abdenacer, additional, and Takamuku, Toshiyuki, additional

Published
2022
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49. Anion Effects on the Mixing States of 1-Methyl-3-octylimidazolium Tetrafluoroborate and Bis(trifluoromethylsulfonyl)amide with Methanol, Acetonitrile, and Dimethyl Sulfoxide on the Meso- and Microscopic Scales

Author

Takamuku, Toshiyuki, primary, Tashiro, Atsuya, additional, Kawano, Masahiro, additional, Ando, Masatoshi, additional, Ogawa, Akira, additional, Sadakane, Koichiro, additional, Iwase, Hiroki, additional, and Shirota, Hideaki, additional

Published
2021
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